1. Field of the Invention
This invention relates to a poultry breeding method wherein the weight of the individual hens is controlled to the ideal level and more particularly to such a method wherein the weight of the individual hens is controlled by storing the ideal weight of the individual hens in an electronic control device in advance, comparing an electric signal representing the ideal weight of the individual hens with an electric signal representing the actual weight of the individual hens output from an independent cage section, and adjusting the amount of feed supplied to the hens according to the result of the comparison.
2. Prior Art Statement
It is known that the amount of feed (g) required by a laying hen per day is determined by the amount of energy that the hen metabolizes (metabolized energy M (Kcl)).
Moreover, the amount of metabolized energy M depends on the weight of the hen W (Kg), the ambient temperature T (.degree.C.), the weight of eggs laid per day E (g), and the daily gain in body weight G (g).
In one experiment it was found, for example, that EQU M=279-59.5W+25W.sup.2 -3.65T+2.26E+5G
Thus if the weight W of the hen is 1.7 Kg, the hen house temperature T is 20.degree. C., the daily egg weight E is 53 g, and the daily weight gain G is 2 g, EQU M=306.88 (Kcl)
The metabolized energy M being equal to the energy ME (Kcl) of the feed multiplied by the amount of feed consumed, it follows that EQU ME.times.(amount of feed consumed)=M
And if the energy ME of the feed normally used is 2900 KCl per Kg, it follows that ##EQU1##
Thus, under the conditions of the aforesaid experiment, each hen should be supplied with about 106 g of feed per day.
As the body weight W of the hen increases each day by the daily weight gain G, however, it is necessary to make a daily adjustment in the amount of feed supplied to the hen in accordance with the ideal weight gain curve.
In the conventional method, this adjustment is generally made, not daily, but about once a week. More specifically, a certain number of hens constituting a sampling are removed from their cages once per week and weighed, and the average weight of the sampled hens is used for calculating the amount of feed to be supplied to all of the hens.
In this conventional method, the work of removing the hens from their cages is extremely troublesome. Moreover, the hens themselves experience a high level of terror upon removal from their cages, and this is a cause for reduced laying.
Another problem is that the conventional method does not permit frequent weight checks accordingly it is impossible to carry out daily increases/decreases in the feed supply based on the ideal weight for the hens.
When the amount of feed supplied is less than that based on the ideal hen weight, the weight of the hen will gradually decrease, and the hen will continue laying at the sacrifice of its own weight up to the point where this is no longer possible, whereafter it will stop laying altogether. This leads to a pronounced decrease in the laying rate. On the other hand, supplying the hen with an amount of feed that is greater than that based on the ideal weight of the hen results in wasted consumption of costly feed and a corresponding economic loss. What is more, the hens become too plump, which results in a drop in laying rate and excessively fatty hens.